China Brings Back the High Temperature Pebble Bed Type Nuclear Reactor.

[NNadir]

China's demonstration HTR-PM enters commercial operation

Subtitle:

The world’s first modular high temperature gas-cooled reactor nuclear power plant has entered commercial operation, China’s National Energy Administration has announced.

Excerpts:

It follows a successful 168-hour demonstration run for the High Temperature Gas-Cooled Reactor - Pebble-bed Module (HTR-PM) in Shidao Bay (also known as Shidaowan), in Shandong Province, which is currently operating at 2×200 MWt power.

The HTR-PM features two small reactors (each of 250 MWt) that drive a single 210 MWe steam turbine. It uses helium as coolant and graphite as the moderator. Each reactor is loaded with more than 400,000 spherical fuel elements (‘pebbles’), each 60 mm in diameter and containing 7 g of fuel enriched to 8.5%. Each pebble has an outer layer of graphite and contains some 12,000 four-layer ceramic-coated fuel particles dispersed in a graphite matrix. The fuel has high inherent safety characteristics, and has been shown to remain intact and to continue to contain radioactivity at temperatures up to 1620°C - far higher than the temperatures that would be encountered even in extreme accident situations, according to the China Nuclear Energy Association.

First concrete for the demonstration project was poured on December 2012, with the operating permit granted in August 2021 and the plant connected to the grid in December 2021. ​The plant has more than 2200 sets of first-of-a-kind equipment, including more than 660 sets of innovative equipment. The supporting fuel element production line has the largest production capacity in the world...

The reactor operates at 500°C with a helium moderator/coolant. This type of reactor is probably not sustainable because the world supply of helium will run out within a few decades, I think, although small but trivial amounts will be available from the decay of tritium (³He) and alpha decay in nuclear fuels, particularly those running on the higher actinides, americium and curium.

500°C is too low to run the SI cycle for water splitting to provide captive hydrogen. My understanding is that the experimental HTR10 run in China did run at temps this high, and if I recall correctly, an SI (sulfur iodine) cycle was explored with this reactor.

Nevertheless, the reactor has been designed for the purpose of producing process heat, which allows for increased exergy recovery and efficiency.

It's nice to see.

In the United States a reactor along similar lines is being designed, but the working fluid is not helium, but is rather a molten salt, bringing to reactor concepts together. This reactor is under development by Kairos, under the scientific leadership of Per Petersen at UC Berkeley. The type of fuel, with refractory Silicon Carbide layers is known as "TRISO" fuel.

The British AGCR which is a commercial bulk fuel option has similar features. The United States operated (briefly) a similar type of reactor at Ft. St. Vrain in Colorado in the 1960's, but the materials science was not well enough developed and the reactor was problematic and was converted to a dangerous natural gas plant.